patches and added features need to be reviewed by project owners.
open source mostly mean "you can read the source and modify your version, but that doesn't mean you can make a change that will go into the official release."
There are some very sensitive implementations of software which should be thoroughly examined by experts and criticized if they're not good enough. If there is no resources available to maintain a particular open source software, don't bother use it, ESPECIALLY if it's sensitive like openssl.
Open source allows software companies and other programmers to easily work together to solve a problem. Developer's time is precious so it's often time-saving to use somebody's else work, but that doesn't mean you should use it blindly.